1. Field of the Invention
The present invention relates to an improved process for preparing ceramic moldings using mountain leather as a part of raw materials.
Ceramic moldings using mountain leather have been heretofore described in publications.
In Japanese Patent Publication No. 45602/1972, a process for preparing flame-resistant paper comprising mountain leather or mountain wood, short fibers of which being closely contacted with each other, which process comprises adding water to beaten mountain leather or mountain wood to give a paste-like product, filtering the resulting paste-like product to remove foreign matters therefrom and then subjecting to paper-making is described.
In Japanese Patent Publication No. 43485/1976, heat-resistant sheets prepared by dispersing ceramic fibers in water using sepiolite as a binder and sucking the dispersion in vacuum, etc. and the use of colloidal silica or colloidal alumina as the binder in combination with sepiolite are disclosed.
In Japanese Patent Publication No. 58480/1982, there is disclosed flame-resistant sheets which are obtained by dispersing inorganic fibers or synthetic fibers (fibers comprising organic, synthetic polymers) in an aqueous dispersion of mountain leather and making the dispersion paper-like form.
These prior arts have their limitation on formulation since it is primarily aimed at imparting flame resistance and heat resistance to the sheet-like products per se.
Mountain leather is an inorganic substance which has peculiar properties that it may per se form sheets having mechanical strength to a certain extent. However, the mechanical strength is still insufficient and particularly in complicated secondary processing such as corrugating, the mechanical strength is unsatisfactory. To compensate for the insufficient mechanical strength, it is generally known to use cellulose pulp or organic polymers, etc. in combination. However, these materials have contradictory tendencies that if the content of organic substance increases, the strength increases but the characteristic properties of inorganic substance such as heat resistance, etc. are lowered; if the content of the organic substance decreases, the properties of inorganic substance such as heat resistance, etc. are enhanced but the mechanical strength decreases. Accordingly, the prior art materials involve a drawback that utility is greatly limited as they are.
Aqueous dispersion of mountain leather is of poor drainage rate as compared to ordinary wood pulp or stuffs. As a result, although it has been possible to manually make short sheet products containing mountain leather as a binder, paper-making of continuous sheet products using paper-making machine was impossible.
As a result of extensive investigations in an attempt to eliminate the foregoing drawbacks in the present circumstances, the present inventors found out that properties required in unburned state and properties required after burning may be separately imparted to the product. The present invention has been accomplished based on such finding.